With the crisis associated with diminishing amounts of fossil fuel and the rapidly increasing prices for this fuel, there has been a great deal of interest in reducing the amount of fuel consumed by automobile engines, and the like.
Thus, there is a great need to find lubricants that reduce the overall friction in the engine, thus reducing the energy requirements thereto.
U.S. Pat. No. 4,201,684 teaches lubricating oils containing sulfurized fatty acid amides, esters or ester-amides of alkoxylated amines, which reduce friction between sliding metal surfaces in internal combustion engines.
U.S. Pat. No. 4,167,486 teaches lubricating oils containing certain acid esters having double bonds or the dimer or trimer of such acid esters. Reductions in fuel consumption in an internal combustion engine are claimed by using the lubricating oils in the crankcase of the engine.
U.S. Pat. No. 3,151,077 teaches the use of borated monoacylated trimethylol alkanes as motor fuel and lubricating oil additives. The additives are taught to reduce the incidence of surface ignition in an internal combustion engine and to inhibit the build-up of carburetor deposits.
U.S. Pat. No. 2,795,548 discloses the use of lubricating oils compositions containing borated glycerol monooleate. The oil compositions are used in the crankcase of an internal combustion engine in order to reduce oxidation of the oil and corrosion of the metal parts of the engine.
There is a problem with the use of borated fatty acid esters of glycerol in lubricating oils since they are sensitive to moisture and hydrolyze readily. The hydrolysis leads to haze and/or precipitate formation which must be filtered out prior to use. Also, glycerol oleate which is generated as a result of the hydrolysis causes bearing corrosion problems and/or precipitate problems in the presence of certain zinc dihydrocarbyl dithiophosphonates and metal phenates.
It has now been found that the borated fatty acid esters of glycerol may be stabilized against hydrolysis in a lubricating oil by using the borated fatty acid esters in conjunction with an alkenyl succinimide.
Most importantly, it has now been found that lubricating the crankcase of an internal combustion engine with a lubricating oil containing a borated fatty acid ester of glycerol reduces the fuel consumption of the engine.